This invention relates to a superconducting magnet winding in general and more particularly to a device for holding the housing of a superconducting magnet winding.
A known device for holding a winding housing provided for a superconducting magnet winding, which can be cooled to a low temperature, is surrounded by at least one protective radiation shield which can be kept at a comparatively higher temperature. The radiation shield and winding housing are arranged in an outer housing which is approximately at room temperature. The holding device comprises at least one rigid tubular support element which is arranged between the outer housing and the winding housing and is connected to the protective radiation shield, and consists, at least partially, of poorly heat-conducting material. Such a holding device is described in a report of the "National Accelerator Laboratory", USA, No. TM-334A, 2791.000 dated Dec. 10, 1971, and entitled "Tne Heim Column".
In superconducting magnet devices, a winding housing, in which the superconducting magnet winding to be cooled is contained, is frequently arranged within a vacuum or outer housing which is at room temperature of about 300 K. This winding housing can therefore likewise be cooled down to the low temperature of the magnet winding and is therefore also called the helium housing. For thermal reasons, at least one protective radiation shield or housing is also provided between the outer housing and the winding housing. The radiation shield is kept, in general, at a temperature between about 40 K and 100 K. For such a structure a holding device with tension or support elements for all three axes is required, through which amounts of heat as small as possible are to be transmitted to the cooled structural parts. For the design of such a holding device, dynamic force components must be considered, in addition to the existing weight masses of the parts, such as forces occurring due to accelerations in the case of shipping.
Because of these requirements, the most varied tension or support elements have been used heretofore, using different materials such as 18/8 CrNi steel, titanium or fiberglass-reinforced plastics. Accordingly, the holding device known from the report cited above consists of several support elements which must be arranged between the outer housing and the winding housing and can be connected to a radiation protection shield.
Each support element contains three tubular parts enclosing each other. The outer tube adjacent to the winding housing as well as the inner tube adjacent to the winding housing consists of fiberglass-reinforced plastic. The tubes are connected to each other via a central tube of aluminum. By using these materials with different expansion characteristics and on the basis of suitable design of the individual tube lengths, a form-fitting as well as friction-force connection via the support elements between the outer and the winding housing can always be assured during the assembly of the entire structure at room temperature as well as in operation of this housing at the low temperature.
Such nolding devices, however, are either overdesigned, so that they can assume the additional stresses during transport, or special transport supports are provided which must be removed before the magnet device is set in operation. Overdesigned holding devices, however, lead to large heat losses, while additional shipping supports make the magnetic device more difficult to handle.
It is therefore an object of the present invention to improve the holding device mentioned at the outset in such a manner that relatively small amounts of heat are transferred from the outer housing to the cooled winding housing and that, nevertheless, the additional dynamic stresses occurring during transport can be intercepted without additional transport supports.